In my application i find few VSAM files used in CICS COBOL programs were not having DSN name defined. I used CEMT I FILE() command to check the presence of DSN name in the CICS region but i could not get the DSN name and FCT entries. I checked the file name in CSD file, dsn nsme is not present. Apart from FCT, is there anyway that VSAM file can be accessed ( i dont think so) since i am not a system programmer i need clarification on this Also i read through IBM manuals regarding dynamically defining FCT for VSAM, Is there any chance multiple filename can be defined for one VSAM DSN? Is there anyway to check the presence of DSN of VSAM apart from CEMT I FILE and searching in CSD?

Send an email to CICS Admin at your site. They should be able to help you.
Have you check the CICS JCL? you can override the DSNAME at run time by specifying the DD name and DSNAME for the file which will use the provided value.

You need to understand that there are 3 places you can define a file. FCT, CSD and CICS JCL.

All those 3 options, are not dynamic. So any dynamic change, will not affect them the next time the CICS restarts.

A file can be defined multiple times with a different DSN name (CSD, FCT and JCL). The JCL dataset name definition takes precedence over the DSNAME of the FCT or CSD.

If you dynamically change the name of the dataset of the tile, next time the CICS restarts, if the definition is in the CICS JCL or the FCT, it will overwrite what was defined dynamically.
If the definition of the dataset name is in the CSD, it will be overwritten only if the CICS starts in COLD status (or initial).

I echo Rohit's recommendation -- you REALLY need to contact your site support group. If, for example, your site is using MRO and you're looking at the TOR (Terminal-Owning Region) while the data set is defined in the FOR (File-Owning Region), then you won't necessarily see any link between the FCT and the DFHCSD entry -- partly because they are different CICS regions, and partly because the TOR and FOR could be using different DFHCSD data sets. And the data set name would be in the TOR, so you would not usually see it in the TOR.

I echo Rohit's recommendation -- you REALLY need to contact your site support group. If, for example, your site is using MRO and you're looking at the TOR (Terminal-Owning Region) while the data set is defined in the FOR (File-Owning Region), then you won't necessarily see any link between the FCT and the DFHCSD entry -- partly because they are different CICS regions, and partly because the TOR and FOR could be using different DFHCSD data sets. And the data set name would be in the TOR, so you would not usually see it in the TOR.

True.
But most likely in this case, the file will be specified as remote with no other settings.

Data Tables (a fancy name for a VSAM file) is used (in my opinion) as Read-Only as writing to it will defeat its overall purpose.

Rather than define the FCT entry as a data-table, define it to an efficient LSR Pool as well as efficient CISIZE's for data and index. Your CICS Sysprog would probably be the person to consult with on this matter.

Data-Tables are moved to extended-storage at CICS startup and therefore, accessing records from them is much more efficient, as most VSAM path logic is eliminated.